Maximize tape lifespan best practice?

What is best practice to maximize tape lifespan:

Append backups to the tape until it becomes full, then overwrite it before the next usage.

or

Overwrite the tape before it becomes full (for example: when used space is 70% or every month even it's not full)?

Solution 1:

If you use only 70% of the tape, than the lifespan will be proportionally longer. However, then you have to use more tapes.

Lifespan depends on the number of end-to-end passes, that is how many times the tape was completely moved from one reel to the other.

Writing the tape to full capacity means several end-to-end passes, because only a limited number of tracks are written in a single pass. For example writing a 400GB raw capacity LTO-3 tape requires 44 passes. If you only use 70% of the tape then those data is written in 44*70%, that is about 31 passes.

You can overwrite the same place on the tape as many times as you wish, that does not seriously limit the lifespan. But moving the tape from one reel to the another does.

The Wikipedia article on LTO tapes describes this technology quite well: Linear Tape-Open